What exactly does implantation cramping feel like?

I feel a little silly asking this, considering I've been pregnant before (unfortunately, it ended in miscarriage), but I'm not sure I experienced implantation cramping with my prior pregnancy. I did have period-like cramping off & on before I got my BFP...would that be considered implantation? The reason I ask is because I'm not due for AF until late next week and I'm having some mild, period-like cramping going on. I'm about 7-8 days DPO. What do you ladies think? Has anyone here experienced implantation cramping? Thanks so much for any advice! :o)